The islands were visited (1471) by Pedro Escobar and João Gomes, the Portuguese explorers, and in 1483 the São Tomé settlement was founded. They were proclaimed a colony of Portugal in 1522. The Dutch held the islands from 1641 to 1740, when they were recovered by the Portuguese. Until the establishment of a slave-based plantation economy in the 18th cent., the islands were used mainly as supply stations on the shipping routes to Brazil and India.
São Tomé and Principe became an overseas province of Portugal in 1951 and received local autonomy in 1973. Following the 1974 military coup in Portugal, the new government recognized the islands' right to independence, granting it on July 12, 1975. Manuel Pinto da Costa, leader of the Gabon-based Movement for the Liberation of São Tomé and Principe (MLSTP), became the country's first president, and his party the sole legal one. The first years were marked by economic hardship caused by the departure of both the Portuguese and a large number of foreign workers. A severe drought and depressed cocoa prices hurt the economy during the 1980s.
A new constitution adopted in 1990 officially ended one-party rule. In 1991, the MLSTP lost the legislative elections and Miguel Trovoada, running unopposed as an independent candidate, won the country's first free presidential election. Principe was granted local autonomy in 1994 (effective 1995). A military coup in 1995 ended peacefully when the president was restored to office and parliament granted the rebel soldiers amnesty.
In July, 1996, Trovoada, this time running against former president Pinto da Costa, was reelected. The MLSTP, which had dominated parliament since 1994, won a majority of seats in the 1998 legislative elections. Inflation, unemployment, and the inability of the government to pay workers resulted in a series of strikes and demonstrations in the 1990s. Fradique de Menezes, the candidate of the opposition Independent Democratic Action party (ADI), was elected president in 2001; his main opponent was Pinto da Costa. In the parliamentary elections the following year, however, the MLSTP won a slim plurality of the seats.
In July, 2003, members of the military, complaining of social and economic decline, ousted President de Menezes, but an agreement was negotiated that resulted in his return to office. The development of offshore oil led to conflicts in the government in 2004 and accusations of corrupt practices; the president ultimately removed the prime minister and entire cabinet. Parliamentary elections in Mar.–Apr., 2006, resulted in a victory for the Force for Change Democratic Movement–Party for Democratic Convergence coalition (MDFM-PCD), which secured a plurality of the seats.
In July, 2006, de Menezes was reelected to the presidency. The MDFM-PCD–led government resigned in Feb., 2008, and a new government, led by the ADI, was formed. Four months later the new government lost a confidence vote, and a new coalition, led by the MLSTP and including the PCD and MDFM, was formed. Several dozen people were arrested on charges of attempting to overthrow the president in Feb., 2009. The Aug., 2010, parliamentary elections were won by the ADI. Pinto da Costa, running as an independent, was elected to succeeded de Menezes in Aug., 2011. The ADI minority government was dismissed in Dec., 2012, and replaced by an opposition coalition.